In this time of environmental awareness, there is a need for materials which are easily degradable for various uses including personal care products or for packaging products. Many times, these products are made from polyolefins such as polyethylene or polypropylene which are not considered as degradable plastic.
Starch has been blended with various plastics to form blends that are partly degradable. For example, European Patent Application No. 388,924 discloses a degradable film comprising a starch blended various polymers such as polyethylene, polyurethane, nylon, polyester and polyvinyl chloride.
As an alternative to blending starch to plastics, copolymers of (meth)acrylate esters and (meth)acrylic acid copolymers were blended with plastics such as polyolefins and modified polyolefins to provide for polymer compositions which are degradable in alkaline solutions. For example, U.S. Pat. No. 5,063,272 discloses a blend of a (meth)acrylic ester/(meth)acrylic acid copolymer and polyethylene glycol which is soluble in alkaline solutions. The relative proportions of the (meth)acrylic ether/(meth)acrylic acid copolymer and the polyethylene glycol depend upon the desired properties of the end product. This polymer blend provides polymeric webs having improved properties suitable for use in personal care products.
U.S. Pat. No. 5,217,795 discloses blends of (meth)acrylic ester/(meth)acrylic acid and modified polyolefins. In addition, these blends can be prepared using styrene/butadiene block copolymers and polyether block amide copolymers. The blends are formed into webs or films. These webs can then be used in absorbent articles.
It has now been discovered that precise, controllable water degradable blend compositions can be formed from blends of polyurethanes and acrylic acid copolymers.